February 2022 Volume 4

State

Stress (MPa)

Time (hrs)

Elongation (%)

MC + HT

710

29.8

20.2

FORGING RESEARCH

NS + HT

710

27.0

25.3

Table 8: Changes to scale C of the Rockwell Hardness Test as grain size decreases.

Grain Size (um) (Long. + Trans.)/2

Hardness (HRC) Long.

Hardness (HRC) Trans.

113

29

32

75

12

14

74

29

30

58

13

13

46

26

29

30

31

19

25

31

30

22

15

16

Table 8: Changes to scale C of the Rockwell Hardness Test as grain size decreases. The mechanical testing :

• Heat treatments: All parts were heat treated through solution (1775 F for 1 hr.) and aged (1325 for 8 hrs, then furnace ramped down to 1150 F then aged for additional 8 hr then air cooled).

Sample: HPM-T2-003 ple: HPM-T2-003 Room temperature tensile test (ASTM E8): 0.2% Offset Yield Strength (ksi) Ultimate Tensile Strength (ksi)

Forging process performed: • 4 pieces of 718 Inconel, henceforth referred to as slugs are the subject of the project. All 4 slugs were placed in a furnace and heated (soaked) at 1800 F. • 2 slugs were removed after 50 minutes of soak time. One is cooled in open air to room temperature (HPM-TAR-003). The second is water quenched to room temperature (HPM- TQR-003). • After cooling, both were returned to the furnace to soak for another 50 minutes. They were then both removed and hit (pressed with 4000 tons of force). • The remaining unforged slugs, slugs 3 and 4, have been soaking during this process. After a total soak time of 2 hours for slug 3, has been removed and hit (HPM-T2-003). • Slug 4 soaks for a total of 4 hours, was removed and hit (HPM-T4-003). The purpose of this project is to simulate a machine failure, press or furnace. By removing the slugs early (slugs 1, 2 and 3) or late (slug 4), we can determine whether these Inconel slugs have mechanical properties similar to a slug that has been appropriately soaked and hit or whether they have become pieces of scrap metal. The mechanical testing : • Heat treatments: All parts were heat treated through solution (1775 F for 1 hr.) and aged (1325 for 8 hrs, then furnace ramped down to 1150 F then aged for additional 8 hr then air cooled).

Reduction of Area (%)

Elongation (%)

178

210

19

33

Elevated temperature tensile test (1200±3 F) (ASTM E 21): 0.2% Offset Yield Strength (ksi) Ultimate Tensile Strength (ksi)

Reduction of Area (%)

Elongation (%)

142

169.5

24

39.5

Stress rupture test (Temperature: 1200 F, Axial stress: 110 ksi) (ASTM E 292): Time to Rupture (hrs.) Elongation (%) 13.3 5.8

Sample: HPM-T4-003 Sa ple: HPM-T4-003 Room temperature tensile test (ASTM E8): 0.2% Offset Yield Strength (ksi) Ultimate Tensile Strength (ksi)

Reduction of Area (%)

Elongation (%)

175

207

21

25

Elevated temperature tensile test (1200±3 F) (ASTM E 21): 0.2% Offset Yield Strength (ksi) Ultimate Tensile Strength (ksi)

Reduction of Area (%)

Elongation (%)

144.5

169

28

50.5

Stress rupture test (Temperature: 1200 F, Axial stress: 110 ksi) (ASTM E 292): Time to Rupture (hrs.) Elongation (%) 26.2 8.9

Sample: HPM-TAR-003 Room temperature tensile test (ASTM E8): 0.2% Offset Yield Strength (ksi) Ultimate Tensile Strength (ksi)

FIA MAGAZINE | FEBRUARY 2022 75

Reduction of Area (%)

Elongation (%)

175

207

20

34